Bleeding disorders pose a significant perioperative risk. Surgeons and surgical consultants should have a working knowledge of the cell-based coagulation model. Careful screening for bleeding diatheses begins with a careful history and physical examination. It is paramount to ascertain what medications and nonprescribed supplements and herbal preparations a patient is taking, as these medications can have significant effects on perioperative bleeding tendencies. Finally, screening laboratory-based coagulation assays are available. These must be used judiciously with regard to a patient's history and the clinical circumstances surrounding the surgical stressor.